Light

Infrared wavesRadio waves Microwaves

Visible light

Ultraviolet X-ray

Gamma Rays

Light Rays

Light is composed of changing electric and magnetic fields running perpendicular to each other. Light does not have to travel through a medium; so it is not a mechanical wave. It is an electro-magnetic wave.

Light fields

Light exerts a field. A field is region around an object that can exert a force to push or pull on an object.

Even though the sun shines millions of miles away, its light field extends all the way to Earth and beyond or we would not be able to see the planets in our galaxy.

Flashlights have light fields that extend in front of the bulb.

Speed of Light

Speed of light. 300,000,000 m/s. Light travels faster in space and slightly slower in matter.

(1) True or (2) False

1. Light waves are called electromagnetic waves.

2. Light waves need a medium.3. A field is region around an object that can

exert a force to push or pull on an object.4. The sun is an example of a light field.5. Light travels faster than sound

Wavelength determines the type of wave and what it can do.

Longest waves (but least frequent) are radio waves. These include the light waves used for radio, television broadcasting, radar, computer applications, etc.

Microwaves

Not as long as radio waves but more frequent, microwaves can be used to cook as well as satellite communication.

Infrared Light

Infrared light has shorter wavelengths than microwaves but are even more frequent. They are used in photography, tracking and keeping food warm.

1) Radio waves 2) Microwaves 3) Infrared waves

a. These have shorter wavelengths than radio waves & can be used in satellite communication.

b. These waves have the highest frequency but shortest wavelength of the three listed above.

c. These include television broadcasting waves.d. These waves have the longest wavelengths but the

shortest frequency of ALL electromagnetic waves.

Visible Light Spectrum

Spectrum means a group of items that gradually change from one extreme to another. The visible light spectrum is the light we can actually see.

ROY G BIV : red, orange, yellow, green, blue, indigo and violetFrom longest to shortest wavelength

Ultraviolet Light

Though it has shorter wavelengths than visible light, ultraviolet light has a higher frequency. The sun gives off UV light which can burn human skin and many florescent lights can emit UV lights.

X-rays

Due to short wavelengths but high frequency, x-rays can penetrate solid objects. As a result it has been used for years in diagnosing internal injuries such as broken bones.

Gamma Rays

The fastest but the shortest light waves, Gamma Rays can penetrate tissue and are used in CT scans and radiation therapy. Too much is a bad thing, since is the same type of radiation that can cause radiation sickness and burns.

1) Visible light spectrum 2) Ultraviolet light 3) X-rays

4) Gamma Rays

1) These waves can penetrate solid objects and are used to diagnosis internal injuries.

2) These are the fastest waves but have the shortest wavelengths.

3) These wavelengths are those we can see4) These waves are the ones that give us sunburn.5) These wavelengths are the colors of the

spectrum.

Light Interactions

Reflection Diffraction

Absorption

Scattering Refraction

Reflection

Reflection occurs when light bounces off an object.

The law of reflection states that the angle between a perpendicular line to a mirror and the beam of light is equal to the perpendicular line and the reflected light

Types of reflection

Light reflects best on smooth surface such as a mirror so that all the beams bounce at the same angle. Light reflects worse on rough surfaces because the beams reflect in many angles.

Absorption and ScatteringAbsorption is the transfer of energy carried by light

waves to particles of matter, as a result the light dims. Scattering is the release of light energy by particles of matter that has absorbed the energy. In the picture shown, air particles have absorbed the light and then scatters it making it look fuzzy.

The edges of shadows are fuzzy due to scattering.

1) Reflection 2) Absorption 3) Scattering

1. When light waves slowly fade away because the energy is transferred to matter (usually a gas)

2. Fuzzy shadows.3. When a wave bounces off a shiny surface.4. The release of light energy by particles of

matter that has absorbed the energy.5. Angle of incidence = angle of reflection

Color

The color of an object is the result of the reflection of light that reaches your eyes. Part of the light is absorbed by the object, the reflection of a particular wavelength is the color you see.

1) Reflection 2) Absorption 3) Scattering

C.D

Refraction

Refraction is the bending of a wave as it passes at an angle from one medium to another.

When light bends it produces a spectrum of color. Different types of light produce different spectrums.

The frequency of the wave, results in the color.

Diffraction

Waves can also bend by diffraction. The amount of diffraction depends on the size of the barrier or opening and the wavelength

1) Refraction 2) Diffraction

Using refraction in reading glasses -- Looking through a concave lens so you

can see near. Shaped like a cave

Using refraction in reading glasses – Looking through a convex lens so you can

see far. Curved outward

1) Concave or 2) Convex

1) Telescope - 2

2) Microscope - 1

3) A peephole in your front door - 2

1) Concave or 2) Convex

Concave Mirrors allow you to see things larger

Convex mirrors allow you to see large areas

1) Concave 2) Convex